3828 research outputs found
Sort by
WePass Störe am Eisernen Tor Wiederherstellung der Durchgängkeit an den Staustufen Iron Gate 1 & 2 in der Unteren Donau
Get PDFDas Einzugsgebiet der 2.857 km langen Donau ist mit einer Gesamtfläche von 801.463 km² - rund 10% des europäischen Festlands - das zweitgrößte Flusseinzugsgebiet in Europa. Es erstreckt sich über 19 Länder und ist damit das internationalste Flusseinzugsgebiet der Welt.
Über 100 Fischarten sind in der Donau nachgewiesen, darunter vier hochgradig gefährdete Störarten, die charakteristischen Flaggschiffarten der Donau (SCHIEMER ET AL. 2004). Die diadromen Donaufischarten (z. B. Störe (Acipenser spp.), Pontischer Maifisch (Alosa immaculata), Asowscher Maifisch (Alosa tanaica) und Schwarzmeerforelle (Salmo labrax)) sind zwingend darauf angewiesen ihren Lebenszyklus im Süß- und Salzwasser zu vollziehen. Einige Arten wandern bzw. wanderten dabei über sehr große Distanzen, beispielsweise der Beluga-Stör (Huso huso) vom Schwarzen Meer bis zu den Laichgründen >2.500 km ins Landesinnere (SCHMALL & FRIEDRICH 2014). Aber auch potamodrome Arten migrieren in der Donau über weite Strecken; für Döbel (Leuciscus cephalus), Barbe (Barbus barbus) und Nase (Chondrostoma nasus) sind z. B. Wanderungen über 169, 318 und 446 km nachgewiesen (STEINMANN ET AL. 1937, VAN TREECK ET AL. 2022).
Die Fischartenzusammensetzung und der Fischbestand sind wichtige Indikatoren für die Gewässerqualität der Donau. Die Ergebnisse des jüngsten Joint Danube Survey 4 zeigen, dass die Fischartengemeinschaft entlang des gesamten Flusslaufs bedroht ist. Andererseits ist die Vielfalt der Fischtaxa immer noch auf einem Niveau, als dass wirksame Gewässerentwicklungsmaßnahmen dazu beitragen können den ökologischen Zustand bzw. das ökologische Potential zu verbessern und die Ziele der EG-WRRL zu erreichen (BĂNĂDUC ET AL. 2014, ICPDR 2021)
Prioritizing conservation and monitoring areas in the Danube River basin: Insights from the DANUBE4all project
Get PDFThe Danube River basin currently lacks a comprehensive action plan for restoring its freshwater and transitional water ecosystems, despite some efforts to address continuum disruptions in upstream regions. The DANUBE4all project aims to address these challenges by identifying, selecting, and recommending implementation measures to increase the extent of free-flowing rivers throughout the entire basin. One of the specific objectives of the project involves identifying suitable habitats for both protected and invasive species, prioritizing conservation actions. To accomplish this, we initially modeled the habitat suitability of the fish species that inhabit the Danube basin. Fishes were chosen because they are good indicators for longitudinal connectivity. This modeling process involved spatially explicit species distribution models, which were trained using environmental data and information on species occurrences. Following the habitat suitability modeling, we conducted a spatial conservation planning analysis. This analysis aimed to pinpoint regions across the Danube River basin that are of high priority for future conservation and monitoring efforts. Priority areas were identified based on the presence of suitable habitats for fish species and the facilitation of longitudinal connectivity within the river system
Modeling of Orange Carbon Dots-CO2 Interaction and Its Effects on Photosynthesis and Productivity in Maize and Green Beans
No full textCrop yield increases with a sustained increase in leaf photosynthesis. Due to many limitations, plants do not sufficiently
use their photosynthetic capacity. Carbon dots (CDs) have a high light harvest capability, which may be used to improve the photosynthesis
efficiency of plants. In this study, nontoxic orange CDs (o-CDs) were foliarly applied to boost the maize (Zea mays L.) and green
beans (Phaseolus vulgaris L.) productivity in the field. Leaves of both plant species were sprayed three times with 1 and 5 mg/L of the
o-CDs aqueous solutions in equal intervals during the vegetative growth stage until flowering. To find the best geometries for CO2 adsorption
on o-CD, modeling of o-CDs-CO2 interaction was performed. Photosynthesis parameters and fruit yield were measured during
plant growth. Total phenolic content and antioxidative activity were monitored as oxidative stress indicators. Computational simulations
and spectroscopic measurements suggest that o-CDs, acting as a “CO2 delivery” system, can enhance photosynthetic efficiency. Photosynthesis
was enhanced in both plant species, but only green beans showed an increased fruit yield. CO2 use in tested species was discussed
in light of two mechanisms. Plant species show different, but no significant antioxidative responses. The chemical surface composition
has shown that o-CDs were not contained in either the leaves or fruits of the treated plants. The results indicate that o-CDs may be
applied as a simple and safe biostimulator on plants. That could have an environmental benefit in capturing CO2 in the atmosphere
How Do Mixed Cover Crops (White Mustard +Oats) Contribute to Labile Carbon Pools in an Organic Cropping System in Serbia?
No full textSustainable farming is one of the priority goals of the “4 per 1000” concept with regard to the preservation of soil fertility and carbon sequestration. This paper presents a study on the use of a mixture of cover crops of self-grown oats (Avena sativa L.) and sown white mustard (Sinapis alba L.) in organic farming under the agroecological conditions of Serbia. The main objective was to identify sensitive carbon pools (microbial carbon and nitrogen, basal respiration and a number of specific groups of soil microorganisms) in organic farming with and without cover crops. The inclusion of a mixture of white mustard and self-grown oats as a cover crop led to a significantly increased biogenity of the soil compared to a control after only a few years of investigation. The number of microorganisms, soil respiration and microbial biomass carbon were significantly higher in the cover crop treatment compared to the control soil on an organic farm in Serbia. This is the first study in Serbia to investigate the effect of self-grown oats as a cover crop. Further research will incorporate a wider range of variables and factors in order to develop a sustainable and effective site-specific system for organic crop production in Serbia
Динамика односа науке и идеологије и зачеци нуклеарног програма у контексту друштвено-економске трансформације ФНРЈ
No full textDuring the Cold War, both blocs aimed to shape science, as well as conceptions about its role in society. Two perspectives on science prevailed: the perspective of free and apolitical science in the Western Bloc and the perspective of partisanship in science in the Eastern Bloc. The concept of big science became an important characteristic of scientific endeavors, especially in fields such as (nuclear) physics. Before the break with the USSR in 1948, the Yugoslav system was characterized by emulation of the Soviet model in all spheres of society, which also applied to the sphere of science. This dissertation looks into the consequences in the area of scientific organization and scientific discourse of the socioeconomic transition of the Yugoslav socialist system, which followed the turbulent break with the USSR. Using the Cold War scientific perspectives, I compare the organization of science and the scientific discourse in Yugoslavia before the break, to the period after the break, when the Yugoslavia, at least in the beginning, strongly turned towards the Western Bloc. Retaining the socialist ideology, but exposed to the dynamics of decentralization and, to a larger extent than before, to market forces, Yugoslav socialism acquired a specific form. This novel configuration has positioned Yugoslav science in the direction of the Western conception of the nature and the role of science in society (primarily with the emphasis on autonomy and decentralisation). Thus, while tracing those occurrences, I will analyse Yugoslavia's attempt to construct a big science project by presenting the development of the Yugoslav nuclear program within the context of the Cold War and geopolitical and socioeconomic dynamics in the (semi)peripheral Yugoslavia.Током Хладног рата, циљ оба блока био је да обликују науку, као и схватања о њеној природи и улози у друштву. Преовладавале су две перспективе: перспектива слободне и аполитичне науке у Западном блоку и перспектива партијности у науци у Источном блоку. Концепт велике науке постао је важан елемент разних научних подухвата, нарочито изражен у областима попут (нуклеарне) физике. Пре раскида са СССР-ом 1948, југословенски систем тежио је ка успостављању совјетског модела у свим сферама друштва, самим тим и у сфери науке. Овај рад бави се последицама насталим услед друштвено-економске транзиције југословенског социјалистичког система, првенствено у области научне организације и научног дискурса, која је уследила након бурног раскида са СССР-ом. Користећи поменуте хладноратовске перспективе о науци, у раду се пореди организација науке и доминантног научног дискурса у Југославији пре раскида, са периодом када се југословенски систем након раскида, бар у почетку, снажно окренуо ка Западном блоку. Задржавајући социјалистичку идеологију, а изложен динамици децентрализације и, у већој мери него раније, тржишним силама, југословенски социјализам добија специфичан облик. Ова нова конфигурација усмерила је југословенску науку ка западном схватању природе и улоге науке у друштву (пре свега по питању аутономније и процеса децентрализације у науци). Стога, док пратимо овај развој, у раду се анализира покушај Југославије да направи пројекат у складу са концептом велике науке, кроз испитивање развоја југословенског нуклеарног програма у контексту Хладног рата и друштвено-економске динамике у (полу)периферном југословенском систему
Morphological Characterization of Green Synthesized ZnO Nanoparticles using Citrus reticulata Blanco Peel or Extract
No full textCitrus reticulata Blanco waste was used as the green capping/reducing agent in green sol gel
synthesis of ZnO nanoparticles (NPs). The effect of using peel powder or aqueous extract and
Zn nitrate/acetate precursors on the synthesized ZnO NP morphology was observed by scanning
electron microscopy (SEM) and transmission electron microscopy (TEM) combined with
scanning transmission electron microscopy (STEM). The formation of pure hexagonal phase
ZnO NPs has been confirmed by X-ray diffraction [1] and was correlated with high resolution
transmission electron microscopy (HRTEM) and selected area diffraction (SAED) analysis. All
samples exhibited a hexagonal wurtzite structure with an average crystallite size between 7.6
and 26.58 nm [1]. SEM and TEM images showed that the morphology of the synthesized NPs
varied depending on the used Zn precursor (nitrate or acetate) and reducing/stabilizing agent
type (peel or extract). ZnO NPs synthesized using Zn nitrate precursor and peel/extract as the
reducing/stabilizing agent during the synthesis process exhibited two classes of nanoparticles.
The combination of Zn nitrate and C. reticulata extract resulted in the formation of pure phase
ZnO NPs without the need for a calcination step with small rounded particles and a bimodal
particle size distribution with two peaks at 5 and 13 nm, and overall average NP size of 9 nm.
EDX analysis confirmed the same ZnO composition. Calcination at 400 °C for 1 h resulted in
a slight increase in NP size, bimodal NP distribution, but dominant smaller particle content and
average NP size of 15 nm. When the nitrate precursor was used in combination with C. reticulata
peel powder even though there were some larger particles, the particle size distribution
gave an average particle size of 14 nm. When the acetate precursor was used in combination
with C. reticulata peel powder the morphology was more uniform showing a homogenous
distribution of NPs whose size ranged between 8 and 26 nm with an average size of 15 nm.
When the acetate precursor was used in combination with the C. reticulata aqueous extract four
different types of particles were obtained: larger needles (150-360 nm), plates (90-120 nm) and
hexagonal nanoparticles (50-85 nm) and small nanoparticles (6-10 nm).
References:
[1] Z.Z. Vasiljevic et al, ACS Appl. Bio Mater. 7 (2024) 3014-3032
Tin sulfide film as a potential photocatalyst for the degradation of methyl orange
No full textTin sulfide films have a great potential for application in a wide range of fields, such as opto-electronic materials [1], lithium-ion batteries [2], electrical switching [3], sensors [4], photocatalysis [5] and more. Azo-dyes are frequently used dye in the textile industry and methyl orange is well-known azo dye that is easily detectable making it a suitable representative for tracking water pollution [6]. Utilizing photocatalysis for MO degradation represents an advanced method to eliminate this dye from water-based environments. In that purpose, tin sulfide film was synthesized on fluorine doped tin oxide (FTO) covered glass substrates by silar method [7] and it has been characterized by scanning electron microscopy and X-ray diffraction. The optical characterization was performed in order to calculate the energy bandgap. The photocatalytic degradation activity was tested on MO under visible light at different pH levels. The film showed the similar activity at neutral pH and in acidic solution. However, it showed no activity in alkaline solution. This observation aligns with methyl orange’s nature as an anionic dye. In acidic conditions the surface of material is positively charged and interactions with dye molecules is attractive, whereas in alkaline conditions repulsion occurs. This research has a potential application in the photodegradation of azo dyes in both industrial waste water and natural water sources
Spectroscopic assessment of mechanical stimuli response in juvenile Serbian spruce (Picea omorika (Pančić) Purkyne)
No full textThe reaction to gravitropic stress in trees is the formation of reaction wood, in conifers
known as compression wood (CW). It forms on the lower side of the leaning stem. Opposite
wood (OW) is formed on the opposite side to the compression wood in the same growth ring,
while wood from growth rings not containing any CW is termed normal wood (NW). In
slow-growing conifer species, CW typically occurs in a severe form. There are several
physical and chemical indicators of CW.
Aiming to understand the reaction wood response in a slow-growing conifer species we
studied CW formation on the stem sections in juvenile P. omorika trees subjected to oneyear
static bending using microscopic and spectroscopic techniques. The sections were
imaged using a Leica SP5 II confocal microscope. The analysis of fluorescence emission
spectra was performed by the non-linear fitting using the Nelder–Mead simplex algorithm
implemented in MATLAB. Since lignin is the primary fluorescent compound in wood cell
walls, the emission spectra reveal the structural properties of lignin and their changes as a
consequence of mechanical stimulation. The results indicate a change in lignin structure
including flurophore type along the stem, from the base to the top segment. This change
varies across the growth rings. The Pyrolysis-GC analysis of individual phenolic and sugar
compounds from the three stem segments, as well as brightness data for 488 nm excitation
confirmed a change in fluorophore type and variation in compression severity from the basal
to the top segment
Determination of the antioxidant activity of the wild Pomegranate (Punica granatum L.) peel extract obtained by Supercritical CO2 extraction
No full textPomegranate (Punica granatum L.) fruit is a rich source of various bioactive compounds and has been used in traditional medicine for treating many medical conditions [1, 2]. Pomegranate peel is also rich in bioactive compounds with phenolic being the primary source of its diverse health benefits, owing to their antioxidant, anti-inflammatory, and antimicrobial properties [1, 2]. Despite this, pomegranate peel is often discarded by the food industry as fruit waste [3]. Also, a detailed study of its antiradical activity has never been conducted before. Samples were collected from the area of Mostar, Bosnia and Herzegovina. Herein, the supercritical CO2 extraction of wild pomegranate peel has been employed to obtain an extract rich in polyphenolic compounds. Supercritical CO2 extraction, a green technology method, replaces classical solvent-based extraction, enabling the isolation of plant compounds in their purest form without degradation of the sample [4]. Owing to its high sensitivity and specificity, Electron paramagnetic resonance (EPR) spectroscopy has been utilized to access the extract's scavenging activity against free radical species (DPPH and hydroxyl radicals). The spin-trapping technique was employed to detect activity against short-lived hydroxyl radicals. The results demonstrate that the pomegranate peel extract is a significant free-radical scavenger. It exhibited remarkable selectivity in eliminating hydroxyl radicals (71.3% compared to 23.6% for DPPH), which is particularly noteworthy as hydroxyl radicals are considered the most reactive oxygen radical species, biologically relevant, and responsible for a number of pathologies. These findings underscore the therapeutic potential of pomegranate peel in combating oxidative stress-related medical conditions but also suggest possibilities for further investigation into its mechanism of action and formulation into pharmaceutical or nutraceutical products
Reactive Orange 16 Photodegradation Mechanism in the Presence of TiO2/Polypyrrole Nanocomposite
No full textWith the aim of determining the mechanism of photodegradation of toxic azo dye Reactive Orange 16 (RO16), the TiO2/PPy nanocomposite (PPy = Polypyrrole), containing 1 wt.% of PPy, was produced from the hydrothermally prepared TiO2 and PPy, obtained by chemical oxidative polymerization. Based on XRPD results, the TiO2 was obtained in nanoanatase form with crystallites of 26 nm while FTIR analysis confirmed the presence of PPy. The UV-Vis absorption
spectrum of TiO2/PPy nanocomposite showed a shift of band to higher wavelengths indicating that the presence of PPy enhanced the absorption capacity for visible light. This is important, considering that TiO2 is mainly active in the UV region [1] . The calculated band gap energy value was 3.08(3) eV. The TiO2/PPy demonstrated excellent photocatalytic activity by completely degrading RO16 within 120 minutes under simulated solar light, with degradation described by the
pseudo-first-order reaction kinetics and a rate constant of 0.056(5) min−1. A
detailed analysis of the mechanism showed the following distribution of reactive
oxidative species: 73 % of h+, 20 % of O2•–, and 7 % of •OH. It also revealed that
the photodegradation followed a modified direct Z-scheme heterojunction in which
PPy played an active and irreplaceable role by opening a new reaction pathway.
References
1. Ajmal, A., Majeed, I., Malik, R. N., Idriss, H., Nadeem, M. A. Principles and mechanisms of
photocatalytic dye degradation on TiO2 based photocatalysts: a comparative overview, RSC Adv.
2014, 4, 37003-37026. DOI: 10.1039/c4ra06658